Australia: The Land Where Time Began
The James Marusek hypothesis - End-Permian mass extinction event
In a print only paper at the Lunar and Planetary Science Conference, 2004 Source 1, James Marusek proposed a mechanism that could link very large impacts with the Siberian Traps and Emeishan Traps, in China, as a cause of the Permian mass extinction. According to his hypothesis a cluster of impact events caused a cluster of extinction events; the kinetic energy of several of these impactors was great enough to smash through the crust of the Earth; massive flood basalt eruptions were caused by these deep impactors; a leading cause of extinctions of both terrestrial and aquatic organisms was acidic gases released by the magma.
Marusek carried out a study of the mortality effects of large impacts of comets or asteroids, concluding that the effects are too localised to explain the global-scale extinctions that occurred at both the end of the Permian and end of the Cretaceous. He concluded there is no support for some of the proposed effects such as global firestorms, an impact winter produced by ejecta debris or mega-tsunamis that penetrated deeply onto landmasses.
He points out that there is a significant difference between a large impact of a comet or asteroid and a large nuclear explosion, to which they have been compared. In a nuclear blast the kinetic energy is released in a spherical manner, in all directions, whereas in the case of an impact the kinetic energy is focused along the impact vector. He proposes that a large impactor is capable of penetrating completely through the crust, releasing most of its kinetic energy deep within the mantle, especially at places of thin crust, as in an ocean impact, the process being called acoustic fluidisation, the crust being liquefied by the impact, the impactor penetrating through to the mantle in a process analogous to that of a shaped charge projectile penetrating the armour of a tank. The deep impactors differ from surface impacts in that they don't throw up a world-wide debris field and leave no crater, large scars or crustal uplift burying most of the debris from the impact.
In his theory the impact energy is the sum of the energy released deep in the mantle and that released at the surface. The surface component of energy release can be approximately that of a large nuclear blast, with the thermal radiation effects. The effects of energy released in the mantle can only be seen in massive eruptions of flood basalt, the formation of a deep magma hotspot and interior structure anomalies, as in the reversal of magnetic poles. Marusek also suggests the energy released deep in the earth can be greater than that released at the surface by an order of magnitude. According to this proposal, the surface scar of a deep impactor may indicate an object of much smaller size than the actual object, most of the evidence being beneath the surface, most of the impact energy being released as heat and momentum transfer deep within the Earth. Tectonic plate joints would be flexed by the shock wave produced by a deep impactor causing large fractures in the floor of the ocean leading to massive undersea flood volcanic eruptions, that could occur at these seams around the world.
However, most of the destructive energy of the shock wave would be focused at the exit vector, travelling through the Earth at speeds greater than those connected with a primary earthquake, about 20,000 mph, and devastating a large area of crust on the opposite side of the Earth. If the exit vector is close to a continent/ocean crustal seam the damage would be greater because of the weakness of the flex joint at the hinged joint. Extensive crustal damage can result upsetting of the delicate balance, with fracturing and derailment of plates.
According this theory, the Emeishan Traps were caused by the fracturing of the crust by the shock wave from the impact of the Guadalupian-Lapingian Boundary. As a result of this impact, an acidic tuff bed about 2 m thick was formed, and large amounts of airborne ash was produced, spreading over thousands of kilometres, and the oceans became anoxic as a result. Another deep impact occurred at the Wuchiapingian-Changshingian Boundary, making the oceans superanoxic, a condition that lasted for more then 10 million years, and causing a magnetic reversal.
The Siberian Traps resulted from yet another deep impact, the crust near eastern Russia being damaged, resulting in terrestrial flood volcanic basaltic eruptions. The Siberian Traps produced 3-5 million km3 of lava, as well as a magnetic reversal. The flood volcanic eruptions at both the Siberian Traps and the Emeishan Traps lasted for more than 10 million years. A marine ecological disaster resulted from the submarine eruptions and the terrestrial eruptions caused a terrestrial ecological disaster, as well as adding to the marine disaster. The primary cause of the extinctions is suggested to have been the release of acidic gases from the magma, resulting in rapid die-offs, on a geological time scale, the collapse of both the marine and terrestrial ecosystems at the end of the Permian taking no more than a few tens of thousands of years.
Flood basalt eruptions generally produce much more magma than volcanoes, Marusek compares the Mt St Helens eruption of 1980 that produced 0.5 km3 of magma with Lakagigar Eruption in Iceland that produced 14.7 km3 of basalt. The eruptions that produced the Siberian Traps released 3,000,000-5,000,000 km3 of basalt. Among the gases produced by volcanoes are water vapour, carbon dioxide, carbon monoxide, sulphur dioxide, hydrogen, hydrogen sulphide, hydrogen chloride, hydrogen fluoride, helium.
The Russian-Ukrainian Theory of Deep Abiotic Petroleum Origin
This is a highly controversial theory, at least in the west, that claims oil deposits are not of biological origin. Some arguments for and against are presented here. It has been claimed that no oil fields have been discovered by basing oil exploration on the theory. It seems that in Russia there are a large number of oil fields that have been discovered using the theory. There doesn't appear to be many supporters of the theory outside Russia. If this theory does prove to be correct it could explain the presence of carbon dioxide and carbon monoxide in the magma that is released in eruptions. According to the theory, the hydrocarbons were basic components of the Earth, and are present in a stable state on the underside of the Earth's crust. During eruptions small amounts of hydrocarbons that leak into the magma burn on being exposed to the atmosphere to produce gases such as carbon dioxide and carbon monoxide, and at the same time taking oxygen from the atmosphere.
Extinctions in the oceans
The marine kills on a massive scale that led to the extinctions would have been caused by the acidification of the oceans. The acidic gases that caused the acidification of the oceans originated mostly in the massive amounts of magma released in the flood basalt eruptions, the Siberian Traps and the Emeishan Traps, with contributions from the impact site, and at the seams of tectonic plates. The thermal radiation associated with the fireball at the impact site would have produced nitric oxide and nitrogen dioxide. A firestorm that it also triggered would also have added more combustion gases to the atmosphere. The vast quantities of carbon dioxide produced would have settled towards the lowest point on the Earth's surface, the oceans, because of its density. Some of the acidic gases would have combined with atmospheric water which then fell as acid rain.
There would have been many places around the Earth where the plates were flexed and cracked, especially at plate seams and the ocean crust, as it is about a tenth as thick as the continental crust. This would have allowed vast quantities of basalt to erupt all around the world.
The mass extinction events occurred in 3 separate episodes, that are considered to be tightly constrained, on a geological time scale. The first occurred at the Guadalupian-Lapingian Boundary (GLB), the second at the Wuchiapingian-Changshingian Boundary (WCB) and the third, the largest, at the Permian-Triassic Boundary (PTB).
The extinctions at the end of the Permian occurred over a span of about 5-8 million years. At this time rooted trees died off rapidly and the insects underwent their only known mass extinction. A number of these impactors are suggested to have been large enough to punch completely through the crust to produce deep impact effects, shock destruction being focused on the opposite side of the Earth fracturing the crust at continent/ocean seams to produce the Emeishan and Siberian Traps, where the eruptions of surface flood basalts were produced over prolonged periods, leading to extensive acid rain. He also suggests large fractures were produced in the ocean floor along the joints of tectonic plates, the resulting volcanic eruptions injecting acidic gases into the ocean, then as the gases bubbled to the surface the gas scrubbing contributing further to ocean acidification. In this reaction carbon dioxide reacts with seawater producing carbonic acid, which then dissolved calcium carbonate. Hydrogen sulphide and sulphur dioxide in these gases react with the seawater and oxygen to produce sulphuric and sulphurous acid. These acids form gypsum (calcium sulphate) when they react with calcium carbonate. The attack of the acidification on calcium carbonate caused the very large affect on marine invertebrates that mostly have calcium carbonate forming the outer covering, their exoskeleton.
He suggests 'evolutionary weaknesses' of the marine organisms, as well as terrestrial organisms, were targeted by this acidification, resulting in a massive die-off at the end of the Permian.
Groups that were lost during this mass extinction include - all trilobites, the most diverse groups at the time, all fusulinids, all blastoids, all rugose and tabulate corals, 90 % of families and 95 % of genera of brachiopods, 98 % of crinozoa species, 96 % of anthozoans, 97 % of ammonoids, 59 % of bivalves, 8 families of ostracods, 85 % of gastropods, 79 % of bryozoans.
Carbonate biomineralisation needs the acid-base balance to be controlled delicately, making organisms that produce exoskeletons of calcium carbonate very sensitive to hypercapnia. In marine animals increased CO2 levels, as little as a few Torr, can cause hypercapnic acidosis, those with gills and active circulation can compensate, at least to some extent, for increased CO2 levels. The growth and reproduction of marine animals can be retarded by the acidity of the water, and can cause unconsciousness and death.
The large amounts of gypsum, produced by sulphur-based acids and calcium carbonate, and framboidal pyrite, produced when hydrogen sulphide reacts with dissolved iron, in the strata of the Permian-Triassic Boundary are evidence of the acidification of the oceans. Greatly reduced oxygen levels in the oceans and hydrocarbon chains produced at the deep sea/magma interface also contributed to extinctions. When the hydrocarbon chains that were in contact with the magma of very high temperatures came in contact with seawater a natural cracking process takes place producing aromatics and turpenes that killed marine organisms as they rose through the water column.
Ecosystems on the land were severely affected by a number of gases that were released by flood basalt eruptions, such as sulphur dioxide, carbon dioxide and hydrogen fluoride. Sulphur dioxide was ejected high into the atmosphere during active eruptions. Because of the high reflectivity of the sulphate aerosols part of the solar radiation was reflected back into space, with the effect of darkening and cooling the surface of the Earth. At this time vast quantities of heat was being released at the surface by the magma where it was prevented from escaping to space, but the evaporation of water carried the heat up past the CO2 of the atmosphere, preventing greenhouse heating. Long dark periods, from several years to decades, resulted from episodes of massive flood volcanic eruptions, reducing photosynthesis they lowered food production, leading to the death of all the levels of the food chain. The sulphur dioxide would eventually fall as acid rain, damaging the photosynthetic plants, compounding the problems of food production.
The global biomass storage has been analysed by Henk Visscher, who studied saprophytic fungi that feed aerobically on woody tissue. At the Permain-Triassic Boundary there was a large fungal spike, indicating excessive dieback of the gymnosperm vegetation. He suggested this was caused by prolonged acid rain. Just such dieback has been found in Germany in the 1980s, where forests, including the Black Forest, have been damaged by acid rain. In the ecosystems of the land the larger trees and shrubs were first selectively removed, the final survivors being the short weedy plants.
The Permian extinctions took place at the tectonic stage when the only landmass was Pangaea and the only ocean was Panthalassa. At the time of the Permian extinctions the synapsids were the dominant land vertebrates, at least partly because of their amniotic eggs that allowed them to move further from water than the amphibians, that were still tied to the water for reproduction. They were badly affected by the extinction event. It has been suggested by Marusek that their reproduction was affected by the acid rain that thinned the calcium carbonate of their egg shells causing them to be brittle and easily broken.
Hydrogen fluoride, another of the gases released by massive flood volcanic eruptions that is toxic at relatively low concentrations. Marusek suggests it was carried high into the atmosphere on volcanic dust and spread widely, eventually falling to cover any still surviving vegetation, making any such vegetation toxic. Fluorine forms soluble salts, as a result of its high reactivity, that would be washed by rain into streams making all surface water in the streams reached toxic.
This effect on the vegetation was demonstrated in 1783 in Iceland following the eruption of Lakagigar. As well as causing a drop of 1o C in the northern hemisphere, most of the livestock in Iceland died after eating grass that had been coated with fluorine. There was also a large-scale crop failure resulting in the deaths of 9,000 people, 1/4 of Iceland's population. At 14.7 km3 of magma, this eruption produced 0.0005 % of that produced by the Siberian Traps eruptions.
He suggests carbon dioxide produced by the eruptions also caused problems because it is heavier than air. By accumulating in low parts of the environment it could reach concentrations sufficiently high to suffocate any animals in the area, as well as affecting plant growth rates that are reduced if the CO2 reaches concentrations above 2,000 ppm.
An unusual feature of the Permian extinction event was the prolonged recovery period, at least 5 million years, plant life recovering in the Middle Triassic with the appearance of a new plant group, that was apparently more tolerant of acidic environments and oxygen stress.
There is some evidence of impacts at the Permian-Triassic Boundary, though not all accept the role of impacts in the extinction event, at least partly because of the lack of carters that could be linked to the event. According to Marusek, large crust-penetrating impacts in the ocean would generate less impact debris than would be produced by continental impacts. In studies of possible impacts that concentrate on crater size and impact markers, would underestimated the significance of these penetrating impacts, as deep impactors do not always form craters, producing impact scar morphology, such as domes or basins with an uplifted core that is volcanic filled, and crumpled, folded landforms. There may be no crater rim around the site of a deep impactor, and there can be gravitational and magnetic anomalies.
200 miles off the coast of Broome in the northwest of Western Australia, the Bedout Structure (Bedout Rise) is considered by Marusek to be impact morphology. The structure that has been dated to 253 +/- 5 Ma has a diameter of 220 km. Another candidate for a penetrating impact is the North Falklands Basin, that is more than 200 km wide and volcanic filled, and has been dated to the Permian-Triassic Boundary. It has also been suggested by Michael Rampino of NASA to be an impact site. There are 3 other very large basins around the Falkland Islands.
The largest known impact structure in South America is the Araguainha Impact Dome in Brazil. It is 40 km across and has been dated to 247-251 Ma. This is also a cluster impact site, the 3-4 other craters ranging from 25-35 km in diameter.
Marusek suggests that the possible ocean impact sites in the Southern Hemisphere have exit vectors in the Northern Hemisphere centred on the Siberian Traps and Emeishan Traps. The pattern of possible impact sites suggest the origin of the impactors was probably the Oort Cloud, as impacts of Kuiper Belt bodies usually strike in the planetary plane.
Layers containing unusually high concentrations of rare earth elements are markers indicating extraterrestrial impacts. Europium has been found in the Permian-Triassic Boundary layer in the Himalayas in India (Shukla et al., 2000).
Iridium peaks were found in the Permian-Triassic Boundary layer in China, Soviet Armenia, Carnic Alps in Austria, and the Dolomite Alps. The concentrations in the Permian-Triassic Boundary layer are 10-100 times lower than those in the Cretaceous-Tertiary Boundary. The concentration of iridium is not directly proportional to the size of the impactor.
Shocked quartz is another mineral indicating impacts. In Antarctica, shocked quartz has been found on Graphite Peak and Mt. Crean and at Wybung Head in Australia. It is believed these locations were some distance from the impact site because of the small size and low abundance of the shocked quartz.
Fullerenes (Buckminsterfullerenes), the 3rd natural form of elemental carbon, are another impact indicator. Though rare on Earth they are much more abundant in space. Fullerenes containing noble gases have been found at Meishan, south China, Sasayama, southwest japan and Graphite Peak, Antarctica. It has been suggested these fullerenes arrived "intact" in the impactor. Extraterrestrial origin was determined by analysis of helium and argon extracted from the fullerenes.
Microspherules, microscopic glass droplets formed in the atmosphere as molten rock cools rapidly, as well as in deep space, have been found in the Permian-Triassic Boundary layer at Sasayama in the Tanba Belt in Japan, South China, Guizhou Province, China, Bukk Mountains in Hungary and the Carnic Alps in Austria. The concentrations of nickel in the spherules tested was >2.25 %, indicating extraterrestrial origin. The composition of aluminium and trace elements in the microspherules indicated an interstellar origin.
Magnetic microspherules with very unusual magnetic properties were found in sediment from the Permian-Triassic Boundary and the Cretaceous-Tertiary Boundary layers. There were iron particles of nano-size exhibiting magnetic moment quenching due to superparamagnetic relaxation. Samples from the Spiti Valley in the Himalayas of India displayed paramagnetic iron phases that could be formed in the extreme pressures and temperatures in an impact vapour plume, but are not normal in terrestrial sediments.
Marusek has listed a number of other effects that he believes would have contributed to the cataclysmic effect on life at the end of the Permian:
The weakening of the health and vitality of populations, as a result of low sunlight and environmental stressors - acid rain, contaminated soil, abnormal temperatures, degraded atmospheric gases - in plants and environmental stressors and starvation in animals.
A breakdown of the carbon cycle as a result of the mass kills. The breakdown of the conversion of carbon dioxide into organic carbon by plants. The breakdown of the conversion of organic carbon to calcium carbonate in bones, exoskeletons, for long-term sequencing [sequestering?], resulting from the loss of animal life.
|Author: M.H.Monroe Email: email@example.com Sources & Further reading|